Infrared radiation system

ABSTRACT

A plurality of electrically powered ceramic heating and radiating elements, each having a flat radiating side and being shaped in the form of a square or rectangle, is arranged and supported by profile girders to form a closed, consistent, and flat radiating surface framed by reflecting sidewalls.

United States Patent 1 1 Steinmetz Jan. 7, 1975 [54] INFRARED RADIATION SYSTEM 3,001,054 9/1961 Fehner 219/345 3,012,128 12/1961 Clamp 219/351 [76] lnventor' Stemmetz, seldeweg 3,471,682 10/1969 Hisey et a1. 219/354 Nofthelmr Germany 3,761,678 9/1973 ECkleS 219/343 [22] Filed: Feb. 22, 1973 FORElGN PATENTS OR APPLICATIONS 21 App], 334,773 1,082,763 6/1954 France 219/345 69,149 4/1958 France.... 219/354 1,113,357 12/1955 France 219/354 [30] Foreign Application Priority Data 110,064 10/1947 Switzerland. 219/352 Feb. 23 972 Germany n 20 54 493,771 ltaly 219/353 Feb, 23, 1972 Germany 7206777 Primary Exammer-J. V. Truhe 52 us. c1 219/352, 219/345, 219/354, Assistant Examiner-clifford Shaw 338/297 Attorney, Agent, or FirmR01and l. Griffin [51] Int. Cl. H05b 3/20 58] Field of Search 219/344, 345, 354, 350, [57] ABSTRACT 219/351, 352, 353, 355, 356, 357, 339, 342, A plurality of electrically powered ceramic heating 343, 405,411, 476, 478, 213;; 338/293, 297 and radiating elements, each having a flat radiating side and being shaped in the form of a square or rect- [56] References Cited angle, is arranged and supported by profile girders to UNITED STATES PATENTS form a closed, consistent, and flat radiating surface 2,744,987 5/1956 Marvin 338/297 framed by reflectmg s'dewans' 2,979,595 4/1961 Deacon 219/345 8 Claims, 7 Drawing Figures k LIL W I 3 V 7 8 I 1 l a 26 I8 7 2 24 24 L2! j I L Patented Jan. 7, 1975 3,859,498

- 5 Sheets-Shet 1 FIG. 1

4 FIG.'2

Patented Jan. 7, 1975 3,859,498

5 Sheets-Sheet 2 Patented Jan. 7, 1975 5 Sheets-Sheet 5 "FIG. 3

.FIG. 4 A

Patented Jan. 7, 1975 3,859,498

5 Sheets-Sheet 4 Patented Jan. 7, 1975 3,859,498

5 Sheets-Sheet 5 1 INFRARED RADIATION SYSTEM BACKGROUND AND SUMMARY OF THE INVENTION This invention is related to an infrared radiation system for heating goods of different kinds, for example, heating plastic folia before they are deformed. Such radiating systems serve to transmit heat in the form of radiation to the goods to be heated, the radiating element or the radiating system, respectively, always being located at a certain radiating distance relative to the goods to be heated.

There are known radiating surfaces composed of several radiating elements, where each radiating element is located in its own housing. The housings of the radiating elements are then connected with each other by means of an additional profile construction. Furthermore, it is known to locate several radiating elements one after the other in a series in a corresponding housing and to form several of these housings into a radiating system. The radiating elementsv used for this purpose have in all instances a curved cross section such that a plurality of curved radiating surfaces is always coacting. With radiating systems of this kind unheated gaps necessarily exist which affect the goods to be heated. In case a small radiation distance is required, such as, for example, when the system is closely packaged, the goods will not be uniformly heated. There are many disadvantages in consequence of such irregular heating.

These shortcomings can only be overcome to a certain extent by increasing the radiating distance. However, in many cases this is not possible and is not advisable because of the required power consumption.

A further disadvantage of prior art radiating systems is the limited flexibility in combining the radiating elements located in the individual housings. Thus, such radiating elements are not usable for the whole variety of applications. In addition, the inevitable peripheral losses of known radiation systems also affect the uniform-heating of the surface of the goods to be heated.

The prior art radiating elements with curved radiating surfaces consist of ceramic bodies in each of which coils of electrical resistance wire are imbedded. Because of this special arrangement 'such radiating elements are typically located at a great radiating distance relative to the goods to be heated. Especially in cases in which the uniformity of the radiating field or the local constancy, respectively, of the transmitted radiating power should be guaranteed, only relatively great radiating distances should be considered. However, in some applications this can be a disadvantage, and it may even happen that the radiating elements cannot be used at all because of the limited space available. Another shortcoming of prior art radiating elements is their relatively great mass and consequently their low heat-up speed.

Thus, it is the problem of this invention to avoid the disadvantages of the prior art and to provide an infrared radiating system having a consistent radiating surface with a comparatively small radiating distance. The radiating system should be arranged such that it can be adapted for as many applications as possible. Furthermore, peripheral losses should be avoided or compensated. In addition, the assembly of the radiating system should be simplified by the arrangement of the individual components of the system. The individual radiating elements should also have a specifically high heat-up speed.

The infrared radiating system of this invention is characterized in that it employs individual ceramic heating and radiating elements each having a substantially flat radiating side and a square, rectangular, or otherwise polygonal contour, and in that these individual ceramic heating and radiating elements can be utilized with further identical or similar radiating elements to form a closed, consistent, and flat radiating surface. The underlying principle of the invention is to form flat radiating elements without mutual interference by housing sections such that even with a small radiating distance a consistent flat radiating surface is formed.

The radiating surface is framed by reflecting sidewalls in order to overcome a radiation loss at the periphery of the system. No housing or wall sections are located between the individual ceramic radiating elements with individual radiating surfaces. The ceramic radiating elements which form the total radiating surface have the form of flat tiles. Thus, individual flat radiating surfaces are formed that are substantially consistent with each other such that in fact the desired consistent total radiating surface of the system is achieved.

It is especially advantageous to form the radiating surface from a set of ceramic radiating elements having the form of tiles and being flat on their radiating sides. In this connection not only small square radiating elements but also radiating elements of twice or four times the area of the small square radiating elements can be used. By a delicate stepping of the radiating elements it is therefore possible to accommodate the particularities of all applications. Thus, the dimensions as well as the power of the radiating system can be accommodated. For example, individual ceramic radiating elements which are located at the peripheral region of the system can be supplied with a relatively higher individual power than the radiating elements in the central region of the system to compensate for peripheral losses. It is also possible to achieve a locally and time differentiated temperature curve by such powering when the goods to be heated are moved relative to the radiating system.

For mounting the radiating elements a rack is formed which consists of composable profile girders. According to the individual dimensions of the radiating elements, profile girders of different widths can be used. The profile girders substantially have the same individual features. They merely have different widths corresponding to the individual widths of the-radiating elements. The rack and the reflecting sidewalls serve as a housing for the totality of the radiating elements of such a system, but not for the individual radiating elements themselves. A special suspension or housing construction as used in the prior art is thus superfluous.

The profile girders forming the rack have guides and frames for inserting coupling elements which connect the profile girders with each other and/or with the reflecting sidewalls. These coupling elements are formed in an especially simple manner and allow a quick assembly of the radiating system in connection with correspondingly shaped profile girders. The profile girders forming the rack have at least partially hollow profiles into which enforcing profiles of heat resistive material can be inserted for operation at increased temperatures.

The preferred embodiment of the infrared radiating system of this invention forms a self-supporting unit which allows an especially small radiating distance. This solves further application problems. The delicate stepping of the radiating elements allows a better adaptation of the radiating surface to given spatial conditions. Furthermore, a better radiating geometry relative to the surface of the goods can be achieved as compared to the prior art, and in some cases it may be possible to decrease the dimensions of the radiating system.

The infrared radiating system substantially consists of individual electrically powered ceramic heating and radiating elements. Electrical resistance wire is located in the form of a coil on the flat radiating side of each radiating element such that the windings of the coil are spaced an equal distance from each other and are parallel to the contour of the radiating element. According to another embodiment, the distance between the windings is smaller in the peripheral region than it is in the central region of the radiating element in order to compensate peripheral losses.

It isespecially advantageous to form each radiating element as a hollow body having a flat front side which carries the resistance coil and having a curved backside which is provided with a frame for inserting the current connectors and for mounting the radiating element. Because of the hollow body, the proper radiating surface has a small mass which results in a high heat-up speed. The resistance windings protrude over the substantially flat radiating surface of each radiating element such that the radiating surface of each radiating element is increased. Furthermore, it is possible to arrange the resistance windings of each radiating element in the form of a plurality of coils which form atotal radiating sur face, where the windings are parallel to the contour of the radiating element.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional elevational view of a radiating system according to the preferred embodiment of this invention.

FIG. 2 is a top view of the backside of a comer part of the radiating system of FIG. 1. The cross-sectional elevational view of the radiating system of FIG. 1 is taken along the lines I-I in FIG. 2.

FIG. 3 is a plan view of the complete radiating system of FIG. 1 on a reduced scale.

FIG. '4A is a plan view of the front side of one of the heating and radiating elements of FIG. 1.

FIG. 4B is a plan view of the front side of another form of the heating and radiating element of FIG. 4A.

FIG. Sis a plan view of the backside of the heating and radiating element of FIG. 4.

FIG. 6 is a sectional elevational view taken along the lines VI-Vl in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1, 2, and 3, and infrared radiating system according to the preferred embodiment of this invention includes a common housing section which is composed of profile girders 1 and 2 and reflecting sidewalls 3. At the profile girders l and 2 guidance elements 5 and screws 6 are provided. Coupling elements 4 in connection with these guidance elements 5 and screws 6 serve to connect the profile girders l and 2 to each other. The profile girders 2 are connected to the reflecting sidewalls 3 by coupling elements 7 in connection with screws 6. For this purpose the sidewalls 3 include suitably shaped reinforcements 8 which extend over the length of the profile girders. It can be seen that by different combinations of the profile girders l and 2 and of the sidewalls 3 a total housing can be formed which allows adaptation to the different dimensions of the individual radiating systems.

Each profile girder l and 2 has ridges 9 which are located centrally, which extend in the longitudinal .direction of the profile girder, and which serve for mounting connectors 10. The connectors 10 serve to be connected with the wiresfor supplying electrical power to the individual ceramic radiating elements. The profile girder 1 has twice the width of the profile girder 2. While the profile girders 1 and 2 have central sections of equal width, the profile girder 1 has hollow profile sections 11 on both sides into which reinforcement profiles 27 of temperature resistant material can be inserted when the system is operating at elevated temperatures.

Individual ceramic heating and radiating elements l2, l3, and 14 are very important elements of the radiating system. These radiating elements are substantially flat on their radiating side. All individual radiating surfaces of the radiating elements 12, 13, and l4'can be arranged to form a consistent radiating surface 15. Each of the radiating elements 12, 13, and 14 has on its backside a radiating frame 16 which is passed through a corresponding opening 17 in the profile girder 1 or 2 and which is mounted by means of a known mounting element 18.

The radiating elements 12, 13, and 14 which form the radiating surface 15 are each constituted in the form of a flat tile and have a square, rectangular, or otherwise polygonal contour. The radiating elements 12, 13, and 14 always have such contours that they can be arranged to form aconsistent, closed radiating surface 15. According to the illustrated preferred embodiment, each radiating element 12 has a square shape, while each radiating element 13 has the same width but twice the length and each radiating element 14 has twice the length and twice the width of each radiating element 12. A delicately stepped system is thereby achieved which allows adaptation of the dimensions of the radiating system and which additionally allows the desired local distribution of power. For example, it is possible to distribute more power to the radiating elements located in the peripheral regions than to the radiating elements located in the central region of the radiating system. This in combination with the reflecting sidewalls 3 compensates for peripheral losses. As can be taken from the drawing, the radiating elements 12 and 13 correspond to the profile girders 2, while the radiating elements 14 and the profile girders l are always inserted jointly.

As mentioned above, the infrared radiating system is composed of several profile girders l and 2 in its housing section. For this purpose the coupling elements 4 are used. There are also provided coupling elements 7 for mounting the reflecting sidewalls 3 at the profile girders 2. As can be taken from the drawing, the coupling elements 4 and 7 can each be displaced in longitudinal grooves of the profile girders 1 and'2 such that they can be located in the desired position. By screwing the profile girders l and 2 together in connection with the sidewalls 3 a self-supported rack is constituted. This rack has a significantly small weight because of the use of the hollow profiles and, compared with the prior art housings, is relatively small. The connectors can be inserted from above. They are accessible and allow a quick and clear wiring. The radiating elements 12, 13, and 14 are located according to the conditions to be met as to the necessary heat for the goods to be radiated. As a whole, a closed, consistent radiating surface 15 is achieved which has no unheated gaps or parts.

As shown in FIGS. 4A, 4B, 5, and 6, each of the heating and radiating elements 12 comprises a hollow ceramic body 19 which has an internal cavity 25 for decreasing the weight of the radiating element and which has a substantially flat front side 20 and a curved backside 21. On the front side 20 of the ceramic body 19 an electrical resistance wire 22 forms a coil as illustrated. The arrangement can be made such that the coil windings are equidistant from each other, as shown in FIG. 4A. However, it is suitable, especially for the compensation of peripheral losses of the individual radiating element, to choose the distance of these coil windings closer in the peripheral regions than in the central region of the radiating element, as shown in FIG. 4B. The degree of change in distance is selected such that a spatially uniform radiation intensity will be achieved in the plane of the goods to be treated. As can be taken from FIGS. 4A'-B and especially from FIG. 6, the electrical resistance wire 22 protrudes from the front side 20 of the radiating element. Thus, it is located in front of the front side 20 such that the portion of the heat in the direction of the goods to be radiated is especially great.

As shown in FIGS. 5 and 6, a bracket 23 is connected to the ceramic body 19 at the center of the backside 21 thereof. This bracket 23 serves for the insertion and the mounting of the radiating element in a housing or a profile girder. The bracket 23 also accepts the current leads for the resistance wire 22. On the backside 21 of the ceramic body 19 there are also provided traversely extending ribs 24. The ribs 24 are especially thin. Of course, instead of these ribs other kinds of ridges or elevations can be provided. The ribs 24 serve to maintain the correct position of the ceramic body 19 relative to the goods to be radiated (i.e., a canting of the radiating elements in the bracket should be avoided). As can be taken from FIG. 1, the profile girders l and 2 may have corresponding ridges or cams 26 which are sufficiently short such that the ribs 24 do not abut against the cams 26. The cams 26 in connection with the ribs 24 merely limit the angle at which a radiating element 12, 13, or 14 may be canted in the respective profile girder l or 2 and therefore maintain the radiating element in the correct position relative to the goods to be radiated. This feature helps to make the total radiating surface 15 more uniform.

I claim:

1. An infrared radiating system comprising a modular rack; reflecting sidewalls removably engaged with said modular rack to form an enclosure; and a plurality of hollow, modular, ceramic heating and radiating elements supported by said modular rack within said enclosure; each of said heating and radiating elements having a polygonal .contour, having a plane radiating front side on which an electrically-powered resistance element is mounted, and having a spaced backside with a mounting element thereon removably engaged by said modular rack to suspend the associated heating and radiating element from said modular rack and position the plane radiating front side of that heating and radiating element with the plane radiating front sides of the other heating and radiating elements in a common uninterrupted radiating plane below said modular rack and within said enclosure.

2. An infrared radiating system as in claim 1 wherein some of said heating and radiating elements of a first size have a square contour, others of a second size have a rectangular contour twice as large as that of the heating and radiating elements of the first size, and still others of a third size have a square contour four times as large as that of the heating and radiating elements of the first size.

3. An infrared radiating system as in claim 1 wherein the resistance element mounted on the plane radiating front side of each of said heating and radiating elements comprises a coil of electrical resistance wire having equidistantly spaced windings conformed to the contour of the plane radiating front side of the heating and radiating element on which the resistance element is mounted.

4. An infrared radiating system as in claim 1 wherein the resistance element mounted on the plane radiating front side of each of said heating and radiating elements comprises a coil of electrical resistance wire having windings conformed to the contour of the plane radiating front side of the heating and radiating element on which the resistance element is mounted but spaced closer together in the peripheral region than in the central region of that heating and radiating element.

5. An infrared radiating system as in claim 1 wherein the resistance element mounted on the plane radiating front side of each of said heating and radiating elements lies in a plane positioned parallel to the plane radiating front side of the heating and radiating element on which the resistance element is mountedand spaced at least as far as the plane radiating front side from the backside of that heating and radiating element.

6. An infrared radiating system as in claim 5 wherein said modular rack and said heating and radiating elements have protruding ridges to maintain the plane radiating front sides of the heating and radiating elements in said common uninterrupted radiating plane.

7. An infrared radiating system comprising a modular rack of profile girders including mounting elements and further including coupling elements some of which connect adjoining ones of said profile girders together; reflecting sidewalls removably connected to adjoining ones of said profile girders by others of said coupling elements to form an enclosure; and a plurality of hollow, modular, ceramic heating and radiating elements supported within said enclosure by the mounting elements of said rack of profile girders; each of said heating and radiating elements having a polygonal contour, having a plane radiating front side on which an electrically powered resistance element is mounted, and having a spaced backside with a mounting element removably engaged with one of the mounting elements of said rack of profile girders to support that heating and radiating element and position the plane radiating front side thereof with the plane radiating front sides of the other heating and radiating elements in a common radiating plane below said rack and within said enclosure.

8. An infrared radiating system as in claim 7 wherein said profile girders have hollow profile parts into which reinforcement profiles of heat-resistive material are inserted for use under elevated temperature conditions. l 

1. An infrared radiating system comprising a modular rack; reflecting sidewalls removably engaged with said modular rack to form an enclosure; and a plurality of hollow, modular, ceramic heating and radiating elements supported by said modular rack within said enclosure; each of said heating and radiating elements having a polygonal contour, having a plane radiating front side on which an electrically-powered resistance element is mounted, and having a spaced backside with a mounting element thereon removably engaged by said modular rack to suspend the associated heating and radiating element from said modular rack and position the plane radiating front side of that heating and radiating element with the plane radiating front sides of the other heating and radiating elements in a common uninterrupted radiating plane below said modular rack and within said enclosure.
 2. An infrared radiating system as in claim 1 wherein some of said heating and radiating elements of a first size have a square contour, others of a second size have a rectangular contour twice as large as that of the heating and radiating elements of the first size, and still others of a third size have a square contour four times as large as that of the heating and radiating elements of the first size.
 3. An infrared radiating system as in claim 1 wherein the resistance element mounted on the plane radiating front side of each of said heating and radiating elements comprises a coil of electrical resistance wire having equidistantly spaced windings conformed to the contour of the plane radiating front side of the heating and radiating element on which the resistance element is mounted.
 4. An infrared radiating system as in claim 1 wherein the resistance element mounted on the plane radiating front side of each of said heating and radiating elements comprises a coil of electrical resistance wire having windings conformed to the contour of the plane radiating front side of the heating and radiating element on which the resistance element is mounted but spaced closer together in the peripheral region than in the central region of that heating and radiating element.
 5. An infrared radiating system as in claim 1 wherein the resistance element mounted on the plane radiating fRont side of each of said heating and radiating elements lies in a plane positioned parallel to the plane radiating front side of the heating and radiating element on which the resistance element is mounted and spaced at least as far as the plane radiating front side from the backside of that heating and radiating element.
 6. An infrared radiating system as in claim 5 wherein said modular rack and said heating and radiating elements have protruding ridges to maintain the plane radiating front sides of the heating and radiating elements in said common uninterrupted radiating plane.
 7. An infrared radiating system comprising a modular rack of profile girders including mounting elements and further including coupling elements some of which connect adjoining ones of said profile girders together; reflecting sidewalls removably connected to adjoining ones of said profile girders by others of said coupling elements to form an enclosure; and a plurality of hollow, modular, ceramic heating and radiating elements supported within said enclosure by the mounting elements of said rack of profile girders; each of said heating and radiating elements having a polygonal contour, having a plane radiating front side on which an electrically powered resistance element is mounted, and having a spaced backside with a mounting element removably engaged with one of the mounting elements of said rack of profile girders to support that heating and radiating element and position the plane radiating front side thereof with the plane radiating front sides of the other heating and radiating elements in a common radiating plane below said rack and within said enclosure.
 8. An infrared radiating system as in claim 7 wherein said profile girders have hollow profile parts into which reinforcement profiles of heat-resistive material are inserted for use under elevated temperature conditions. 